The best discussion of the rabbinic passages dealing with Elijah and the Messiah remains that of Louis Ginzberg, An Unknown Jewish Sect (New York: Jewish Theological Seminary of America, 1976), chap. 6 (reprint). On page 212, he lists 14 places where Elijah will come to resolve halakhic doubts. On page 242, he discusses the sources in which Elijah and the Messiah are mentioned together.